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On many projects today, the image of sand and cement dumped to mix mortar by hand is gradually being replaced by ready-made mortar bags. So what is ready-mixed dry mortar, how is it different from the traditional mixing method and which type should be chosen for masonry walls and plastered walls? The following article summarizes what homeowners and contractors need to know before putting ready-mixed dry mortar into the project.

What is Ready-Mix Dry Mortar?

Ready-mixed dry mortar is a mixture of cement and sand that has been dried, sieved to sort the particle size and additives, quantified, mixed uniformly at the factory and then bagged. When constructing, the worker only needs to add clean water according to the recommended ratio, mix evenly, and there is mortar to build or plaster.

The core difference lies in the fact that the distribution is controlled from the beginning. Each bag of mortar has the same composition, so the quality of the masonry circuit, plaster between floors, and areas in the same project is more stable than mixing according to the experience of each group of workers.

How is ready-mixed dry mortar different from hand-mixed mortar at the site?

Hand-mixed mortar is still popular because of its familiarity and proactive source of materials. However, when placed next to each other, the two ways of doing it have some obvious differences:

• Grade: hand-mixed mortar depends on the worker's way of measuring sand and cement, which is easy to differ between batches. Pre-mixed dry mortar is dosed by a machine at the factory.
• Sand quality: the sand purchased outside can be mixed with mud, clay, impurities or irregular grains. The sand in the dry mortar has been dried and sieved for sorting.
• Construction site: hand mix the sand and cement gathering yard. The mortar is compact, easy to transport to high floors and suitable for works in the city, tight grounds.
• Loss and cleaning: sand left outdoors is easily washed away and spilled. Bagging mortar is used wherever it is used, the construction site is cleaner.
• Quality control: ready-mixed dry mortar with clear mortar labels and standards, convenient for acceptance supervision consultants.

Advantages of using ready-mixed dry mortar

• The quality is uniform between batches, limiting errors due to mixing the wrong proportion.
• Fast application, just add water and mix with a low-speed stirrer.
• It is easy to calculate the volume of materials according to the norm, reducing redundancy.
• The construction site is neat, less dusty, suitable for townhouses and renovation works.
• It is easy to manage quality when the product is compliant and has a clear label.

Commonly used ready-mixed dry mortars

Depending on the item, ready-mixed dry mortar is divided into many lines with different functions:

• Masonry mortar: used to build terracotta brick walls, aggregate concrete bricks. Refer to HPM ready-mixed dry masonry mortar.
• Plaster: used for plastering interior and exterior walls and concrete ceilings. Refer to HPM pre-mixed dry plaster.
• Finishing grout: create a smooth flat wall and ceiling surface before painting, such as HPM SMOOTH PRO.
• Non-shrinkage pouring mortar: used for machine platforms, column legs, anchor bolts, such as HPM GROUT 600.
• Tile adhesive: used for tiling instead of traditional sand cement mortar, such as HPM TILEBOND series.

What is M50, M75, M100 mortar grade? Which grade to choose accordingly?

The mortar grade shows the compressive strength of the mortar after 28 days. The M50, M75, M100 grades correspond to the compressive strength of about 5, 7.5 and 10 MPa. The higher the grade, the stronger the mortar.

The direction for choosing the grade below is for reference according to the practice of popular construction. For each specific project, the mortar grade needs to be specified in the design dossier:

• M50: usually used for partition walls, non-load-bearing covering walls, indoor items.
• M75: a popular choice for masonry walls, plastering of residential housing, both inside and outside the house.
• M100: for locations that require higher strength or as specified by the design.

HPM ready-mixed masonry mortar and dry plastering mortar are all available in three grades M50, M75, M100 and comply with TCVN 4314:2022 standards.

Reference Dry Mortar Rating

The norms below apply to HPM ready-mixed dry mortar, excluding losses. The actual amount used varies according to the type of tile, wall thickness and surface flatness.

• Masonry mortar: approx. 370 to 400 kg of dry mortar for 1 m³ of single wall, mortar veins about 8 to 12 mm thick.
• Plaster 10 mm thick : about 15 to 16 kg/m².
• Plaster 15 mm thick : about 23 to 24 kg/m².
• Plaster 20 mm thick : about 31 to 32 kg/m².

If you need to quickly calculate the volume of materials for the project, you can use the material estimation tool on the HPM Cement website.

Instructions for the construction of ready-mixed dry mortar with correct techniques

Step 1: Prepare the surface. The surface of the tile or wall needs to be clean, solid, free of grease and impurities. With tiles, the wall absorbs water strongly, moistens it before construction but does not let water stagnate.

Step 2: Mix the mortar. Put clean water in the bucket first at the rate of 17 to 22% of the volume of dry mortar, equivalent to about 8.5 to 11 liters for 1 bag of 50 kg. Slowly pour in the mortar and stir with a low-speed mixer until the mortar is flexible, homogeneous, and not clumped.

Step 3: Building or plastering. For masonry mortar, spread the mortar evenly with a vein about 8 to 12 mm thick, lay the tiles and align when the mortar is still flexible. For plastering, each layer is 8 to 20 mm thick; where it needs to be thicker than 15 mm, it should be divided into two layers to avoid sagging and cracking due to shrinkage.

Step 4: Maintenance. Keep the masonry circuit and plastering surface moist in the early days, especially when it is hot and dry, to limit crow's feet cracking due to rapid dehydration.

Important precautions for use

• Do not add sand, cement or other materials to the ready-mixed dry mortar as it will distort the mixing level.
• Use up the mortar in about 60 to 90 minutes after mixing, do not use the mortar that has started to set.
• Apply when the surface temperature is between 12°C and 40°C.
• Store in a cool, dry place, put on pallets, keep the bag tight and use according to the principle of first-in, first-out.
• The shelf life of HPM ready-mix dry mortar is 6 months from the date of manufacture.

Frequently Asked Questions About Ready-Mix Dry Mortar

Does ready-mixed dry mortar need to be mixed with cement to make sure?

Nope. The grade has been calculated according to the mortar grade. Adding cement or sand may cause the mortar to shrink, crack or reduce adhesion.

Can ready-mix dry plaster plaster concrete ceilings?

Yes. HPM ready-mix dry plaster can be used for interior, exterior walls and concrete ceilings. Surfaces should be cleaned and treated properly before plastering.

How much water does a 50 kg bag of mortar need?

About 8.5 to 11 liters of clean water, equivalent to 17 to 22% of the volume of dry mortar. It is recommended to adjust within this range according to the water absorption of the tiles and weather conditions.

HPM Premixed Dry Mortar for Your Building

HPM Cement provides ready-mixed masonry mortar, dry plaster M50, M75, M100 in accordance with TCVN 4314:2022 standards, as well as tile adhesives and technical mortar lines for many items. The product has been used in projects such as the Thanh Xuan Valley project.

View all HPM products or contact HPM Cement for advice on choosing mortar labels and quotations for the project.